The overall objective of this research program is to understand the role of limited proteolysis in physiological processes. On the biological level we wish to define the variety of processes that are regulated by limited proteolysis of protein treatment while on the molecular level we wish to elucidate the nature of the chemical and conformational changes which are responsible for the attendant biological responses. Limited proteolysis is also being used as a tool in the sequence analysis of proteins as it provides one means of cleaving the polypeptide chains into large fragments which after purification can be used for sequential automated degradation in the protein sequencer. In what follows, we shall describe the progress which has been made during the year of reporting and the program goals which we hope to reach during the coming year.